A general algorithm for computing bound states in infinite tight-binding systems

TL;DR

This paper introduces a robust and efficient wave matching algorithm for computing bound states in infinite tight-binding systems, capable of handling slowly decaying states and those within continuous spectra.

Contribution

The authors develop a novel wave matching-based algorithm that accurately computes bound states in infinite tight-binding systems, including challenging cases with slow decay and embedded states.

Findings

Algorithm successfully computes bound states in various topological materials.

Robustness demonstrated in presence of slowly decaying bound states.

Applicable to quantum billiards, Majorana states, edge states, and Fermi arcs.

Abstract

We propose a robust and efficient algorithm for computing bound states of infinite tight-binding systems that are made up of a finite scattering region connected to semi-infinite leads. Our method uses wave matching in close analogy to the approaches used to obtain propagating states and scattering matrices. We show that our algorithm is robust in presence of slowly decaying bound states where a diagonalization of a finite system would fail. It also allows to calculate the bound states that can be present in the middle of a continuous spectrum. We apply our technique to quantum billiards and the following topological materials: Majorana states in 1D superconducting nanowires, edge states in the 2D quantum spin Hall phase, and Fermi arcs in 3D Weyl semimetals.